The present invention relates to the composite tank arts. It finds particular application in conjunction with maritime chemical tankers having composite storage tanks for use in transporting and storing liquid organic and inorganic chemicals, and will be described with particular reference thereto. The present invention also finds application in conjunction with composite iso-tank containers for use in transporting and storing liquid organic and inorganic chemicals on maritime container ships, railroad cars, and roadway semi-trailers.
Seaborne trade in liquid organic and inorganic chemicals has grown tremendously over the past decade. This growth is accompanied with the ever present dangers of massive ecological damage should any of the present tanker ships have a chemical spill due to collision with another ship or ship breakup due to internal corrosion and/or rough seas.
With the growing demand for the transportation of hazardous chemicals by sea, new designs, safety equipment, and containment procedures have been developed. One such design is full, double-hulled ships with the port and starboard wings being used to carry less hazardous cargoes. Further, due to the inability of present coatings to resist the corrosive effects of the more aggressive cargoes, more and more chemical tanker's cargo tanks are being built of stainless steel. However, the cost for the stainless steel tanks can, on larger chemical tankers, cost as much as the rest of the ship, including the steel hull, engine room equipment and outfitting.
A major problem facing maritime chemical tanker operators and owners is the time spent in port which remains very long in relation to time spent at sea. Chemical tanker owners and operators face a port time of their entire fleet of deep-sea tankers of around 40%. This causes a tremendous loss in charter revenue. This port time is, in part, due to the requirement of washing and cleaning the cargo tanks prior to loading the next cargo. With present tanker designs, which incorporate integral rectangular stainless steel cargo tanks, large hard to reach surfaces have to be washed down with chemicals to remove the residue of the previous cargo. This takes an excessive amount of time plus it produces large quantities of hazardous waste water, typically referred to as "slops". Slops have to be treated and neutralized before being pumped overboard, or have to be pumped ashore for treatment. In either case, washing known rectangular stainless steel cargo tanks is a very costly and time consuming process.
It has been proposed to build cylindrical stainless steel tanks which are easier to clean. The use of cylindrical stainless steel cargo tanks reduces the amount of slops required to clean the cargo tanks, reduces the time spent in port cleaning the tanks, and reduces the costs associated with neutralizing the slops that are produced. However, it is more expensive to manufacturer cylindrical stainless steel cargo tanks. Thus, the use of cylindrical stainless steel cargo tanks increases the manufacturing cost of the ship, reduces carrying capacity of the cargo tanks due to loss of area of a cylinder versus that of a rectangle, and increases the weight and length of the ship in order to carry the same volume of cargo as a ship having rectangular cargo tanks.
Also, the transportation of liquid organic and inorganic chemicals by rail and over-the-road presents numerous hazards to humans, animals, and the environment.
Accordingly, it has been considered desirable to develop a new and improved composite storage tank for transporting and storing liquid organic and inorganic chemicals, which meets the above-stated needs and overcomes the foregoing difficulties and others while providing better and more advantageous results.